Did you replace both ignition coils? Have you replaced the plastic housing that holds the ignition coils? The plastic housing can short causing a misfire. If the ignition system all checks ok don't forget compression and fuel injectors.

I own a 1997 grand am also and have had this problem several times.It is your ignition coil housing that is the culprit. I have replaced mine four or five times since taking the car out of the dealers showroom in 1997.It is very easy to replace yourself and buy the part at O'Reilly Auto Parts where they offer a lifetime guarantee on that particular item.

I would like to update this post. It is the coil housing!! I have a 2000 grand am and had the problem of losing two cylinders. My early symptoms included rough idling, which I ignored. Then one morning on the way to work I noticed a hesitation when I accelerated from 2500 RPM'S (highway speed of 75). When I pulled off the highway about 20 minutes later and RPM's dropped, I had a very rough idle. I stopped for gas and had trouble starting. The next light about a mile down the road I could barely keep it started. I limped to work about 10 miles and started my diognosis. I changed plugs, boots, one bad coil (had them both tested) and 2 injectors (tested with Ohms and two were below 12). None of that worked until I found this post - against all my 'mechanic' friends advice, I replaced the housing and the problem is resolved. My housing had no cracks or signs of wear.